fix windows build

Author: jef-n

src/core/qgslegendrenderer.h

@@ -23,7 +23,7 @@ class QgsSymbolV2;
  *
  * @note added in 2.6
  */
-class QgsLegendRenderer
+class CORE_EXPORT QgsLegendRenderer
 {
   public:
     /** Construct legend renderer. The ownership of legend model does not change */

src/core/qgslegendsettings.h

@@ -13,7 +13,7 @@
  *
  * @note added in 2.6
  */
-class QgsLegendSettings
+class CORE_EXPORT QgsLegendSettings
 {
   public:
     QgsLegendSettings();